UMTS Reselection Parameters

General parameters with typical network values of the three types of reselection in UMTS is presented below:

3G to 3G

• qrxlevmin = -109 dBm     (min acceptable threshold of cell RSCP)
• qqualmin = -18 dB           (min acceptable threshold of cell quality EcNo)

• sintersearch =  10 dB   (f1,f2 case)
• sintrasearch =  14 dB    (same frequency)

3G to 2G

• ssearchrat = 2dB            (indicates when to trigger measurements on GSM cells, increasing this value quickens while decreasing it delays the process)
• treselect = 2s
• qoffset1sn = 7dB for gsmrelation; 0 dB for utranrelation                                                       (Source and target signal offset when reselection strategy is RSCP)
• qoffset2sn = 0 dB                 (Source and target signal offset when reselection strategy is EcNo)

2G to 3G

• FDDqRSCPmin = -102 dBm
• FDDqmin = -12 dB

Equation

The equations on which the decision is made using these parameters are:

For EcNo based reselection:

Squal <= sintrasearch     OR        sintersearch           OR            ssearchrat

where Squal = qmeasured  -    qqualmin

Thus the equation becomes:

qmeas - qqualmin <= sintrasearch

qmeas  <= qqualmin + sintrasearch

Similarly, EcNo values can be replaced with RSCP for the RSCP based reselection.

Mobile Originating Call Flow

Here is the detailed Mobile Originating Call Flow divided into 4 functional modules depicting the network nodes for easy comprehension:

Candidate Cell Priority (HO Priority) - CDR Alcatel-Lucent

Improvement in Quality and reduction in Call Drops can be achieved in Alcatel-Lucent (B11, B10) by proper adjustment of Candidate Cell Priority (HO Priority Level).

Parameter:

• Candidate_Cell_Priority

Target Cells: Radio Drops, HO Drops, Bad UL/DL Quality

Theory: 

• This parameter decides the priority of target cells for each source cell during Handover
• One standard approach is use highest priority for DCS neighbors (0), 2nd highest (1) for less interfered and 3rd highest (2) for others